wheel

1[countable]one of the round objects under a car, bicycle, bus, etc. that turns when it movesHe braked suddenly, causing the front wheels to skid.One of the boys was pushing the other along in a little box on wheels.She was killed when she was crushed under the wheels of a bus.

2[countable,usually singular]the round object used to steer a car, etc. or shipThis is the first time I've sat behind the wheel since the accident.A car swept past with Laura at the wheel.Do you want to take the wheel(= drive) now?see alsohelm,steering wheel

5wheels[plural]wheel (of something)an organization or a system that seems to work like a complicated machine that is difficult to understandthe wheels of bureaucracy/commerce/government, etc.It was Rob's idea. I merely set the wheels in motion(= started the process).

-wheeler

6(in nouns)a car, bicycle, etc. with the number of wheels mentioneda three-wheeler

a situation which is difficult to understand because it involves complicated or secret processes and decisionsThere are wheels within wheels in this organization—you never really know what is going on.